1. Field of the Invention
The present invention relates to controlling particle absorption on a wafer sample, and more particularly to controlling particle absorption on a wafer sample being inspected by a charged particle beam imaging system.
2. Description of the Prior Art
As electronic devices become smaller in size, the processing technique thereof becomes more microscopic. Charged particle beam imaging will likely become one of the critical technologies in advanced semiconductor manufacture. Charged particle beam imaging tools, which include conventional scanning electron microscopes (SEMs) have a much higher resolution than optical tools and are able to detect smaller size defects.
Particles such as dust in atmosphere influence the characteristics or yield of manufactured electronic devices significantly. Due to this, elimination of particles during the manufacturing process is a very important factor. In a microscopic circuit, since the sizes of particles are as large as or even larger than the distance between metal wires, yield (ratio of source material to product) is degraded when particles are adhered to the wafer causing short circuits or other problems.
Conventional methods for removing particles from, for example, a wafer chuck in a testing apparatus include the use of an air gun or nozzle to blow particles away from the chuck. However, this method is only partially effective in removing the particles from the chuck, especially those carrying charges.
Hence, how to control particle absorption on a wafer sample within a charged particle beam imaging system is now urgently needed to target.